Final answer:
Fault creep is the slow process of fault movement causing ongoing infrastructure damage, occurring as tectonic plates slide past each other. It leads to earthquakes when stresses in the Earth's crust build up and are released suddenly. The San Andreas Fault is a notable example with different intervals between major movements and varying degrees of slippage.
Step-by-step explanation:
The slow process of fault movement that causes ongoing infrastructure damage is known as fault creep. This phenomenon occurs when tectonic plates slide past each other gradually and not smoothly, which over time can lead to significant stresses within the Earth's crust. In areas such as the San Andreas Fault, this movement can average around 5 cm/year. When these stresses build up to a critical point without being released, they can cause earthquakes. Major slippages can have devastating impacts on nearby regions and result in infrastructure damage.
For instance, at the San Andreas Fault near Parkfield, California, repetitive movement occurs, releasing approximately 1 meter of stress every 25 years or so. Conversely, in regions like Los Angeles, stress may accumulate over longer periods, e.g., 150 years with an average movement of around 7 meters. The last significant slip in Los Angeles was in 1857, and since then, infrastructure damage risks have risen due to the mounting tension. Sensitive instruments have evidenced that the Los Angeles basin is distorting as it contracts in response, indicating an immense buildup of underground pressure.